The present invention is directed at an inspection system for packages. In particular, the present invention is directed at a method and apparatus for detecting the presence of a closure on a container and determining whether the closure is properly seated on the container.
In the packaging industry, the quality and preservation of packaged goods depend a great deal upon the quality of the package. One important aspect of package quality is the effectiveness of the closure at sealing the product in the container and protecting it from outside elements. A cocked closure, for example, may allow air and other elements into the container and in contact with the product, resulting in spoilage and/or a reduction in quality or freshness or other adverse effect. Also, a loose fit closure may easily become detached from the container and lead to product spillage. On the other hand, a closure that is set too tight may become difficult or seemingly impossible to remove by the consumer resulting in consumer frustration with the product. Closure set may affect other aspects of product packaging, such as the application of a safety seal around the closure, or packaging and product stacking, for example.
Today, automation processes are commonplace for filling containers and packages with a product and securing closures on the containers and packages. Modern equipment can fill containers and apply closures at rates from 300 to 2000 containers per minute and beyond. After a product, which may be a solid, liquid, or gas, is dispensed into a container, a closure is applied to the opening of the container and secured thereto using any one of a number of closure application mechanisms known in the art. Also, safety seals and/or tamper-proofbands may be applied to the container and/or closure before or after the closure is secured to the container. As is well known in the art, the dispensing of the product into the container and the application of the closure on the container, as well as any other seals and/or bands, is performed automatically by machines. Occasionally, the closure is not set properly on the container or is missing. Upon such an occurrence, the package is referred to as a xe2x80x9cdudxe2x80x9d.
Several devices/mechanisms exist for testing a completed package (e.g., to verify that the fill level is within tolerance, the labels are properly positioned, the container is intact and the closure is properly seated). Typically, a package that does not conform to specifications is rejected for disposal or correction.
Devices for testing completed product packages, including jars and bottles, include optical sensors, proximity detectors, linear array cameras, radiation detectors, lasers, and other devices. For example, U.S. Pat. No. 5,895,911 discloses a glass container body detector for locating checks in the bodies of glass containers. It includes a light source and linear array cameras. U.S. Pat. No. 5,864,600 discloses a system having a radiation source and a radiation detector wherein a container situated or moving therebetween blocks portions of the radiation. The radiation detector generates electric signals in response to receiving portions of the radiation not blocked by the container. Processing circuitry determines one or more characteristics of the container from the set of characteristics of a standard container. U.S. Pat. No. 5,369,713 discloses a method for detecting defects in stationary products or products moving on a production line. The product is illuminated by a light source and an image of the product is taken by a sensor. The processor examines areas of interest of the product image and data analysis determines whether a cap is in place and aligned. Also, U.S. Pat. No. 4,472,945 discloses an apparatus for detecting uncapped bottles in which light from a light source located above a bottle is reflected off a cap to a photo tube.
Given the importance of having a closure properly seated on a container and the pace at which modern packaging systems operate, there is a continuing need to have rapid and accurate package inspection systems for ascertaining the position and attitude of a closure on a container.
Accordingly, it is an object of the present invention to provide a method and apparatus for determining the position and attitude of a closure on a container.
It is also an object to provide an apparatus that is sturdy in a package inspection system environment, performs accurately and consistently, and can be easily adjusted to accommodate variations that occur in such a system, such as container height and closure size. Still further objects and measures of the invention will become apparent after consideration of an ensuing description and accompanying drawings.